/*

 * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * VP5 and VP6 compatible video decoder (common features)

 */

#include "libavutil/mem.h"

#include "avcodec.h"

#include "bytestream.h"

#include "decode.h"

#include "h264chroma.h"

#include "vp56.h"

#include "vp56data.h"

#include "vpx_rac.h"

void ff_vp56_init_dequant(VP56Context *s, int quantizer)

{

    if (s->quantizer != quantizer)

        ff_vp3dsp_set_bounding_values(s->bounding_values_array, ff_vp56_filter_threshold[quantizer]);

    s->quantizer = quantizer;

    s->dequant_dc = ff_vp56_dc_dequant[quantizer] << 2;

    s->dequant_ac = ff_vp56_ac_dequant[quantizer] << 2;

}

static int vp56_get_vectors_predictors(VP56Context *s, int row, int col,

                                       VP56Frame ref_frame)

{

    int nb_pred = 0;

    VP56mv vect[2] = {{0,0}, {0,0}};

    int pos, offset;

    VP56mv mvp;

    for (pos=0; pos<12; pos++) {

        mvp.x = col + ff_vp56_candidate_predictor_pos[pos][0];

        mvp.y = row + ff_vp56_candidate_predictor_pos[pos][1];

        if (mvp.x < 0 || mvp.x >= s->mb_width ||

            mvp.y < 0 || mvp.y >= s->mb_height)

            continue;

        offset = mvp.x + s->mb_width*mvp.y;

        if (ff_vp56_reference_frame[s->macroblocks[offset].type] != ref_frame)

            continue;

        if ((s->macroblocks[offset].mv.x == vect[0].x &&

             s->macroblocks[offset].mv.y == vect[0].y) ||

            (s->macroblocks[offset].mv.x == 0 &&

             s->macroblocks[offset].mv.y == 0))

            continue;

        vect[nb_pred++] = s->macroblocks[offset].mv;

        if (nb_pred > 1) {

            nb_pred = -1;

            break;

        }

        s->vector_candidate_pos = pos;

    }

    s->vector_candidate[0] = vect[0];

    s->vector_candidate[1] = vect[1];

    return nb_pred+1;

}

static void vp56_parse_mb_type_models(VP56Context *s)

{

    VPXRangeCoder *c = &s->c;

    VP56Model *model = s->modelp;

    int i, ctx, type;

    for (ctx=0; ctx<3; ctx++) {

        if (vpx_rac_get_prob_branchy(c, 174)) {

            int idx = vp56_rac_gets(c, 4);

            memcpy(model->mb_types_stats[ctx],

                   ff_vp56_pre_def_mb_type_stats[idx][ctx],

                   sizeof(model->mb_types_stats[ctx]));

        }

        if (vpx_rac_get_prob_branchy(c, 254)) {

            for (type=0; type<10; type++) {

                for(i=0; i<2; i++) {

                    if (vpx_rac_get_prob_branchy(c, 205)) {

                        int delta, sign = vpx_rac_get(c);

                        delta = vp56_rac_get_tree(c, ff_vp56_pmbtm_tree,

                                                  ff_vp56_mb_type_model_model);

                        if (!delta)

                            delta = 4 * vp56_rac_gets(c, 7);

                        model->mb_types_stats[ctx][type][i] += (delta ^ -sign) + sign;

                    }

                }

            }

        }

    }

    /* compute MB type probability tables based on previous MB type */

    for (ctx=0; ctx<3; ctx++) {

        int p[10];

        for (type=0; type<10; type++)

            p[type] = 100 * model->mb_types_stats[ctx][type][1];

        for (type=0; type<10; type++) {

            int p02, p34, p0234, p17, p56, p89, p5689, p156789;

            /* conservative MB type probability */

            model->mb_type[ctx][type][0] = 255 - (255 * model->mb_types_stats[ctx][type][0]) / (1 + model->mb_types_stats[ctx][type][0] + model->mb_types_stats[ctx][type][1]);

            p[type] = 0;    /* same MB type => weight is null */

            /* binary tree parsing probabilities */

            p02 = p[0] + p[2];

            p34 = p[3] + p[4];

            p0234 = p02 + p34;

            p17 = p[1] + p[7];

            p56 = p[5] + p[6];

            p89 = p[8] + p[9];

            p5689 = p56 + p89;

            p156789 = p17 + p5689;

            model->mb_type[ctx][type][1] = 1 + 255 * p0234/(1+p0234+p156789);

            model->mb_type[ctx][type][2] = 1 + 255 * p02  / (1+p0234);

            model->mb_type[ctx][type][3] = 1 + 255 * p17  / (1+p156789);

            model->mb_type[ctx][type][4] = 1 + 255 * p[0] / (1+p02);

            model->mb_type[ctx][type][5] = 1 + 255 * p[3] / (1+p34);

            model->mb_type[ctx][type][6] = 1 + 255 * p[1] / (1+p17);

            model->mb_type[ctx][type][7] = 1 + 255 * p56  / (1+p5689);

            model->mb_type[ctx][type][8] = 1 + 255 * p[5] / (1+p56);

            model->mb_type[ctx][type][9] = 1 + 255 * p[8] / (1+p89);

            /* restore initial value */

            p[type] = 100 * model->mb_types_stats[ctx][type][1];

        }

    }

}

static VP56mb vp56_parse_mb_type(VP56Context *s,

                                 VP56mb prev_type, int ctx)

{

    uint8_t *mb_type_model = s->modelp->mb_type[ctx][prev_type];

    VPXRangeCoder *c = &s->c;

    if (vpx_rac_get_prob_branchy(c, mb_type_model[0]))

        return prev_type;

    else

        return vp56_rac_get_tree(c, ff_vp56_pmbt_tree, mb_type_model);

}

static void vp56_decode_4mv(VP56Context *s, int row, int col)

{

    VP56mv mv = {0,0};

    int type[4];

    int b;

    /* parse each block type */

    for (b=0; b<4; b++) {

        type[b] = vp56_rac_gets(&s->c, 2);

        if (type[b])

            type[b]++;  /* only returns 0, 2, 3 or 4 (all INTER_PF) */

    }

    /* get vectors */

    for (b=0; b<4; b++) {

        switch (type[b]) {

            case VP56_MB_INTER_NOVEC_PF:

                s->mv[b] = (VP56mv) {0,0};

                break;

            case VP56_MB_INTER_DELTA_PF:

                s->parse_vector_adjustment(s, &s->mv[b]);

                break;

            case VP56_MB_INTER_V1_PF:

                s->mv[b] = s->vector_candidate[0];

                break;

            case VP56_MB_INTER_V2_PF:

                s->mv[b] = s->vector_candidate[1];

                break;

        }

        mv.x += s->mv[b].x;

        mv.y += s->mv[b].y;

    }

    /* this is the one selected for the whole MB for prediction */

    s->macroblocks[row * s->mb_width + col].mv = s->mv[3];

    /* chroma vectors are average luma vectors */

    s->mv[4].x = s->mv[5].x = RSHIFT(mv.x,2);

    s->mv[4].y = s->mv[5].y = RSHIFT(mv.y,2);

}

static VP56mb vp56_decode_mv(VP56Context *s, int row, int col)

{

    VP56mv *mv, vect = {0,0};

    int ctx, b;

    ctx = vp56_get_vectors_predictors(s, row, col, VP56_FRAME_PREVIOUS);

    s->mb_type = vp56_parse_mb_type(s, s->mb_type, ctx);

    s->macroblocks[row * s->mb_width + col].type = s->mb_type;

    switch (s->mb_type) {

        case VP56_MB_INTER_V1_PF:

            mv = &s->vector_candidate[0];

            break;

        case VP56_MB_INTER_V2_PF:

            mv = &s->vector_candidate[1];

            break;

        case VP56_MB_INTER_V1_GF:

            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);

            mv = &s->vector_candidate[0];

            break;

        case VP56_MB_INTER_V2_GF:

            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);

            mv = &s->vector_candidate[1];

            break;

        case VP56_MB_INTER_DELTA_PF:

            s->parse_vector_adjustment(s, &vect);

            mv = &vect;

            break;

        case VP56_MB_INTER_DELTA_GF:

            vp56_get_vectors_predictors(s, row, col, VP56_FRAME_GOLDEN);

            s->parse_vector_adjustment(s, &vect);

            mv = &vect;

            break;

        case VP56_MB_INTER_4V:

            vp56_decode_4mv(s, row, col);

            return s->mb_type;

        default:

            mv = &vect;

            break;

    }

    s->macroblocks[row*s->mb_width + col].mv = *mv;

    /* same vector for all blocks */

    for (b=0; b<6; b++)

        s->mv[b] = *mv;

    return s->mb_type;

}

static VP56mb vp56_conceal_mv(VP56Context *s, int row, int col)

{

    VP56mv *mv, vect = {0,0};

    int b;

    s->mb_type = VP56_MB_INTER_NOVEC_PF;

    s->macroblocks[row * s->mb_width + col].type = s->mb_type;

    mv = &vect;

    s->macroblocks[row*s->mb_width + col].mv = *mv;

    /* same vector for all blocks */

    for (b=0; b<6; b++)

        s->mv[b] = *mv;

    return s->mb_type;

}

static void vp56_add_predictors_dc(VP56Context *s, VP56Frame ref_frame)

{

    int idx = s->idct_scantable[0];

    int b;

    for (b=0; b<6; b++) {

        VP56RefDc *ab = &s->above_blocks[s->above_block_idx[b]];

        VP56RefDc *lb = &s->left_block[ff_vp56_b6to4[b]];

        int count = 0;

        int dc = 0;

        int i;

        if (ref_frame == lb->ref_frame) {

            dc += lb->dc_coeff;

            count++;

        }

        if (ref_frame == ab->ref_frame) {

            dc += ab->dc_coeff;

            count++;

        }

        if (s->avctx->codec->id == AV_CODEC_ID_VP5)

            for (i=0; i<2; i++)

                if (count < 2 && ref_frame == ab[-1+2*i].ref_frame) {

                    dc += ab[-1+2*i].dc_coeff;

                    count++;

                }

        if (count == 0)

            dc = s->prev_dc[ff_vp56_b2p[b]][ref_frame];

        else if (count == 2)

            dc /= 2;

        s->block_coeff[b][idx] += dc;

        s->prev_dc[ff_vp56_b2p[b]][ref_frame] = s->block_coeff[b][idx];

        ab->dc_coeff = s->block_coeff[b][idx];

        ab->ref_frame = ref_frame;

        lb->dc_coeff = s->block_coeff[b][idx];

        lb->ref_frame = ref_frame;

        s->block_coeff[b][idx] *= s->dequant_dc;

    }

}

static void vp56_deblock_filter(VP56Context *s, uint8_t *yuv,

                                ptrdiff_t stride, int dx, int dy)

{

    if (s->avctx->codec->id == AV_CODEC_ID_VP5) {

        int t = ff_vp56_filter_threshold[s->quantizer];

        if (dx)  s->vp5dsp.edge_filter_hor(yuv +         10-dx , stride, t);

        if (dy)  s->vp5dsp.edge_filter_ver(yuv + stride*(10-dy), stride, t);

    } else {

        int * bounding_values = s->bounding_values_array + 127;

        if (dx)

            ff_vp3dsp_h_loop_filter_12(yuv +         10-dx, stride, bounding_values);

        if (dy)

            ff_vp3dsp_v_loop_filter_12(yuv + stride*(10-dy), stride, bounding_values);

    }

}

static void vp56_mc(VP56Context *s, int b, int plane, uint8_t *src,

                    ptrdiff_t stride, int x, int y, ptrdiff_t ref_stride)

{

    uint8_t *dst = s->frames[VP56_FRAME_CURRENT]->data[plane] + s->block_offset[b];

    uint8_t *src_block;

    int src_offset;

    int overlap_offset = 0;

    int mask = s->vp56_coord_div[b] - 1;

    int deblock_filtering = s->deblock_filtering;

    int dx;

    int dy;

    if (s->avctx->skip_loop_filter >= AVDISCARD_ALL ||

        (s->avctx->skip_loop_filter >= AVDISCARD_NONKEY

         && !(s->frames[VP56_FRAME_CURRENT]->flags & AV_FRAME_FLAG_KEY)))

        deblock_filtering = 0;

    dx = s->mv[b].x / s->vp56_coord_div[b];

    dy = s->mv[b].y / s->vp56_coord_div[b];

    if (b >= 4) {

        x /= 2;

        y /= 2;

    }

    x += dx - 2;

    y += dy - 2;

    if (s->interlaced && s->il_block) {

        /* extract 12*(4+16+4) block from frame (containing both fields), then treat src_block as specific field */

        s->vdsp.emulated_edge_mc(s->edge_emu_buffer,

                                 src + s->block_offset[b] + (dy-4)*ref_stride + (dx-2),

                                 ref_stride, ref_stride,

                                 12, 24, x, y - 2,

                                 s->plane_width[plane],

                                 s->plane_height[plane]);

        src_block = s->edge_emu_buffer;

        src_offset = 2 + 4*ref_stride;

    } else if (x<0 || x+12>=s->plane_width[plane] ||

        y<0 || y+12>=s->plane_height[plane]) {

        s->vdsp.emulated_edge_mc(s->edge_emu_buffer,

                                 src + s->block_offset[b] + (dy-2)*stride + (dx-2),

                                 stride, stride,

                                 12, 12, x, y,

                                 s->plane_width[plane],

                                 s->plane_height[plane]);

        src_block = s->edge_emu_buffer;

        src_offset = 2 + 2*stride;

    } else if (deblock_filtering) {

        /* only need a 12x12 block, but there is no such dsp function, */

        /* so copy a 16x12 block */

        s->hdsp.put_pixels_tab[0][0](s->edge_emu_buffer,

                                     src + s->block_offset[b] + (dy-2)*stride + (dx-2),

                                     stride, 12);

        src_block = s->edge_emu_buffer;

        src_offset = 2 + 2*stride;

    } else {

        src_block = src;

        src_offset = s->block_offset[b] + dy*stride + dx;

    }

    if (deblock_filtering)

        vp56_deblock_filter(s, src_block, stride, dx&7, dy&7);

    if (s->mv[b].x & mask)

        overlap_offset += (s->mv[b].x > 0) ? 1 : -1;

    if (s->mv[b].y & mask)

        overlap_offset += (s->mv[b].y > 0) ? stride : -stride;

    if (overlap_offset) {

        if (s->filter)

            s->filter(s, dst, src_block, src_offset, src_offset+overlap_offset,

                      stride, s->mv[b], mask, s->filter_selection, b<4);

        else

            s->vp3dsp.put_no_rnd_pixels_l2(dst, src_block+src_offset,

                                           src_block+src_offset+overlap_offset,

                                           stride, 8);

    } else {

        s->hdsp.put_pixels_tab[1][0](dst, src_block+src_offset, stride, 8);

    }

}

static void vp56_idct_put(VP56Context *s, uint8_t * dest, ptrdiff_t stride, int16_t *block, int selector)

{

    if (selector > 10 || selector == 1)

        s->vp3dsp.idct_put(dest, stride, block);

    else

        ff_vp3dsp_idct10_put(dest, stride, block);

}

static void vp56_idct_add(VP56Context *s, uint8_t * dest, ptrdiff_t stride, int16_t *block, int selector)

{

    if (selector > 10)

        s->vp3dsp.idct_add(dest, stride, block);

    else if (selector > 1)

        ff_vp3dsp_idct10_add(dest, stride, block);

    else

        s->vp3dsp.idct_dc_add(dest, stride, block);

}

static av_always_inline void vp56_render_mb(VP56Context *s, int row, int col, int is_alpha, VP56mb mb_type)

{

    int b, ab, b_max, plane, off;

    AVFrame *frame_current, *frame_ref;

    VP56Frame ref_frame = ff_vp56_reference_frame[mb_type];

    ptrdiff_t ref_stride[4];

    vp56_add_predictors_dc(s, ref_frame);

    frame_current = s->frames[VP56_FRAME_CURRENT];

    frame_ref = s->frames[ref_frame];

    if (mb_type != VP56_MB_INTRA && !frame_ref->data[0])

        return;

    memcpy(ref_stride, s->stride, sizeof(s->stride));

    if (s->interlaced && s->il_block) {

        s->block_offset[2] -= s->stride[0] * 7;

        s->block_offset[3] -= s->stride[0] * 7;

        s->stride[0] *= 2;

    }

    ab = 6*is_alpha;

    b_max = 6 - 2*is_alpha;

    switch (mb_type) {

        case VP56_MB_INTRA:

            for (b=0; b<b_max; b++) {

                plane = ff_vp56_b2p[b+ab];

                vp56_idct_put(s, frame_current->data[plane] + s->block_offset[b],

                                s->stride[plane], s->block_coeff[b], s->idct_selector[b]);

            }

            break;

        case VP56_MB_INTER_NOVEC_PF:

        case VP56_MB_INTER_NOVEC_GF:

            for (b=0; b<b_max; b++) {

                plane = ff_vp56_b2p[b+ab];

                off = s->block_offset[b];

                s->hdsp.put_pixels_tab[1][0](frame_current->data[plane] + off,

                                             frame_ref->data[plane] + off,

                                             s->stride[plane], 8);

                vp56_idct_add(s, frame_current->data[plane] + off,

                              s->stride[plane], s->block_coeff[b], s->idct_selector[b]);

            }

            break;

        case VP56_MB_INTER_DELTA_PF:

        case VP56_MB_INTER_V1_PF:

        case VP56_MB_INTER_V2_PF:

        case VP56_MB_INTER_DELTA_GF:

        case VP56_MB_INTER_4V:

        case VP56_MB_INTER_V1_GF:

        case VP56_MB_INTER_V2_GF:

            for (b=0; b<b_max; b++) {

                int x_off = b==1 || b==3 ? 8 : 0;

                int y_off = b==2 || b==3 ? (s->interlaced && s->il_block ? 1 : 8) : 0;

                plane = ff_vp56_b2p[b+ab];

                vp56_mc(s, b, plane, frame_ref->data[plane], s->stride[plane],

                        16*col+x_off, 16*row+y_off, ref_stride[plane]);

                vp56_idct_add(s, frame_current->data[plane] + s->block_offset[b],

                              s->stride[plane], s->block_coeff[b], s->idct_selector[b]);

            }

            break;

    }

    if (is_alpha) {

        s->block_coeff[4][0] = 0;

        s->block_coeff[5][0] = 0;

    }

    if (s->interlaced && s->il_block) {

        s->stride[0] /= 2;

        s->block_offset[2] += s->stride[0] * 7;

        s->block_offset[3] += s->stride[0] * 7;

    }

}

static int vp56_decode_mb(VP56Context *s, int row, int col, int is_alpha)

{

    VP56mb mb_type;

    int ret;

    if (s->interlaced) {

        int prob = s->il_prob;

        if (col > 0) {

            if (s->il_block)

                prob -= prob >> 1;

            else

                prob += (256 - prob) >> 1;  /* can be simplified/combined */

        }

        s->il_block = vpx_rac_get_prob(&s->c, prob);

    }

    if (s->frames[VP56_FRAME_CURRENT]->flags & AV_FRAME_FLAG_KEY)

        mb_type = VP56_MB_INTRA;

    else

        mb_type = vp56_decode_mv(s, row, col);

    ret = s->parse_coeff(s);

    if (ret < 0)

        return ret;

    vp56_render_mb(s, row, col, is_alpha, mb_type);

    return 0;

}

static int vp56_conceal_mb(VP56Context *s, int row, int col, int is_alpha)

{

    VP56mb mb_type;

    if (s->frames[VP56_FRAME_CURRENT]->flags & AV_FRAME_FLAG_KEY)

        mb_type = VP56_MB_INTRA;

    else

        mb_type = vp56_conceal_mv(s, row, col);

    vp56_render_mb(s, row, col, is_alpha, mb_type);

    return 0;

}

static int vp56_size_changed(VP56Context *s)

{

    AVCodecContext *avctx = s->avctx;

    int stride = s->frames[VP56_FRAME_CURRENT]->linesize[0];

    int i;

    s->plane_width[0]  = s->plane_width[3]  = avctx->coded_width;

    s->plane_width[1]  = s->plane_width[2]  = avctx->coded_width/2;

    s->plane_height[0] = s->plane_height[3] = avctx->coded_height;

    s->plane_height[1] = s->plane_height[2] = avctx->coded_height/2;

    s->have_undamaged_frame = 0;

    for (i=0; i<4; i++)

        s->stride[i] = s->flip * s->frames[VP56_FRAME_CURRENT]->linesize[i];

    s->mb_width  = (avctx->coded_width +15) / 16;

    s->mb_height = (avctx->coded_height+15) / 16;

    if (s->mb_width > 1000 || s->mb_height > 1000) {

        ff_set_dimensions(avctx, 0, 0);

        av_log(avctx, AV_LOG_ERROR, "picture too big\n");

        return AVERROR_INVALIDDATA;

    }

    av_reallocp_array(&s->above_blocks, 4*s->mb_width+6,

                      sizeof(*s->above_blocks));

    av_reallocp_array(&s->macroblocks, s->mb_width*s->mb_height,

                      sizeof(*s->macroblocks));

    av_free(s->edge_emu_buffer_alloc);

    s->edge_emu_buffer_alloc = av_malloc(16*stride*2);

    s->edge_emu_buffer = s->edge_emu_buffer_alloc;

    if (!s->above_blocks || !s->macroblocks || !s->edge_emu_buffer_alloc)

        return AVERROR(ENOMEM);

    if (s->flip < 0)

        s->edge_emu_buffer += 15 * stride * 2;

    if (s->alpha_context)

        return vp56_size_changed(s->alpha_context);

    return 0;

}

static int ff_vp56_decode_mbs(AVCodecContext *avctx, void *, int, int);

int ff_vp56_decode_frame(AVCodecContext *avctx, AVFrame *rframe,

                         int *got_frame, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    VP56Context *s = avctx->priv_data;

    AVFrame *const p = s->frames[VP56_FRAME_CURRENT];

    int remaining_buf_size = avpkt->size;

    int alpha_offset = remaining_buf_size;

    int i, res;

    int ret;

    if (s->has_alpha) {

        if (remaining_buf_size < 3)

            return AVERROR_INVALIDDATA;

        alpha_offset = bytestream_get_be24(&buf);

        remaining_buf_size -= 3;

        if (remaining_buf_size < alpha_offset)

            return AVERROR_INVALIDDATA;

    }

    res = s->parse_header(s, buf, alpha_offset);

    if (res < 0)

        return res;

    if (res == VP56_SIZE_CHANGE) {

        for (i = 0; i < 4; i++) {

            av_frame_unref(s->frames[i]);

            if (s->alpha_context)

                av_frame_unref(s->alpha_context->frames[i]);

        }

        s->frames[VP56_FRAME_CURRENT]->flags |= AV_FRAME_FLAG_KEY; //FIXME

    }

    ret = ff_get_buffer(avctx, p, AV_GET_BUFFER_FLAG_REF);

    if (ret < 0) {

        if (res == VP56_SIZE_CHANGE)

            ff_set_dimensions(avctx, 0, 0);

        return ret;

    }

    if (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) {

        if ((ret = av_frame_replace(s->alpha_context->frames[VP56_FRAME_CURRENT], p)) < 0) {

            av_frame_unref(p);

            if (res == VP56_SIZE_CHANGE)

                ff_set_dimensions(avctx, 0, 0);

            return ret;

        }

    }

    if (res == VP56_SIZE_CHANGE) {

        if (vp56_size_changed(s)) {

            av_frame_unref(p);

            return AVERROR_INVALIDDATA;

        }

    }

    if (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) {

        int bak_w = avctx->width;

        int bak_h = avctx->height;

        int bak_cw = avctx->coded_width;

        int bak_ch = avctx->coded_height;

        buf += alpha_offset;

        remaining_buf_size -= alpha_offset;

        res = s->alpha_context->parse_header(s->alpha_context, buf, remaining_buf_size);

        if (res != 0) {

            if(res==VP56_SIZE_CHANGE) {

                av_log(avctx, AV_LOG_ERROR, "Alpha reconfiguration\n");

                avctx->width  = bak_w;

                avctx->height = bak_h;

                avctx->coded_width  = bak_cw;

                avctx->coded_height = bak_ch;

            }

            av_frame_unref(p);

            return AVERROR_INVALIDDATA;

        }

    }

    s->discard_frame = 0;

    avctx->execute2(avctx, ff_vp56_decode_mbs, 0, 0, (avctx->pix_fmt == AV_PIX_FMT_YUVA420P) + 1);

    if (s->discard_frame)

        return AVERROR_INVALIDDATA;

    if ((res = av_frame_ref(rframe, p)) < 0)

        return res;

    *got_frame = 1;

    return avpkt->size;

}

static int ff_vp56_decode_mbs(AVCodecContext *avctx, void *data,

                              int jobnr, int threadnr)

{

    VP56Context *s0 = avctx->priv_data;

    int is_alpha = (jobnr == 1);

    VP56Context *s = is_alpha ? s0->alpha_context : s0;

    AVFrame *const p = s->frames[VP56_FRAME_CURRENT];

    int mb_row, mb_col, mb_row_flip, mb_offset = 0;

    int block, y, uv;

    ptrdiff_t stride_y, stride_uv;

    int res;

    int damaged = 0;

    if (p->flags & AV_FRAME_FLAG_KEY) {

        p->pict_type = AV_PICTURE_TYPE_I;

        s->default_models_init(s);

        for (block=0; block<s->mb_height*s->mb_width; block++)

            s->macroblocks[block].type = VP56_MB_INTRA;

    } else {

        p->pict_type = AV_PICTURE_TYPE_P;

        vp56_parse_mb_type_models(s);

        s->parse_vector_models(s);

        s->mb_type = VP56_MB_INTER_NOVEC_PF;

    }

    if (s->parse_coeff_models(s))

        goto next;

    if (s->interlaced) {

       s->frames[VP56_FRAME_CURRENT]->flags |= AV_FRAME_FLAG_INTERLACED;

       s->il_prob = vp56_rac_gets(&s->c, 8);

    }

    memset(s->prev_dc, 0, sizeof(s->prev_dc));

    s->prev_dc[1][VP56_FRAME_CURRENT] = 128;

    s->prev_dc[2][VP56_FRAME_CURRENT] = 128;

    for (block=0; block < 4*s->mb_width+6; block++) {

        s->above_blocks[block].ref_frame = VP56_FRAME_NONE;

        s->above_blocks[block].dc_coeff = 0;

        s->above_blocks[block].not_null_dc = 0;

    }

    s->above_blocks[2*s->mb_width + 2].ref_frame = VP56_FRAME_CURRENT;

    s->above_blocks[3*s->mb_width + 4].ref_frame = VP56_FRAME_CURRENT;

    stride_y  = p->linesize[0];

    stride_uv = p->linesize[1];

    if (s->flip < 0)

        mb_offset = 7;

    /* main macroblocks loop */

    for (mb_row=0; mb_row<s->mb_height; mb_row++) {

        if (s->flip < 0)

            mb_row_flip = s->mb_height - mb_row - 1;

        else

            mb_row_flip = mb_row;

        for (block=0; block<4; block++) {

            s->left_block[block].ref_frame = VP56_FRAME_NONE;

            s->left_block[block].dc_coeff = 0;

            s->left_block[block].not_null_dc = 0;

        }

        memset(s->coeff_ctx, 0, sizeof(s->coeff_ctx));

        memset(s->coeff_ctx_last, 24, sizeof(s->coeff_ctx_last));

        s->above_block_idx[0] = 1;

        s->above_block_idx[1] = 2;

        s->above_block_idx[2] = 1;

        s->above_block_idx[3] = 2;

        s->above_block_idx[4] = 2*s->mb_width + 2 + 1;

        s->above_block_idx[5] = 3*s->mb_width + 4 + 1;

        s->block_offset[s->frbi] = (mb_row_flip*16 + mb_offset) * stride_y;

        s->block_offset[s->srbi] = s->block_offset[s->frbi] + 8*stride_y;

        s->block_offset[1] = s->block_offset[0] + 8;

        s->block_offset[3] = s->block_offset[2] + 8;

        s->block_offset[4] = (mb_row_flip*8 + mb_offset) * stride_uv;

        s->block_offset[5] = s->block_offset[4];

        for (mb_col=0; mb_col<s->mb_width; mb_col++) {

            if (!damaged) {

                int ret = vp56_decode_mb(s, mb_row, mb_col, is_alpha);

                if (ret < 0) {

                    damaged = 1;

                    if (!s->have_undamaged_frame || !avctx->error_concealment) {

                        s->discard_frame = 1;

                        return AVERROR_INVALIDDATA;

                    }

                }

            }

            if (damaged)

                vp56_conceal_mb(s, mb_row, mb_col, is_alpha);

            for (y=0; y<4; y++) {

                s->above_block_idx[y] += 2;

                s->block_offset[y] += 16;

            }

            for (uv=4; uv<6; uv++) {

                s->above_block_idx[uv] += 1;

                s->block_offset[uv] += 8;

            }

        }

    }

    if (!damaged)

        s->have_undamaged_frame = 1;

next:

    if ((p->flags & AV_FRAME_FLAG_KEY) || s->golden_frame) {

        if ((res = av_frame_replace(s->frames[VP56_FRAME_GOLDEN], p)) < 0)

            return res;

    }

    av_frame_unref(s->frames[VP56_FRAME_PREVIOUS]);

    FFSWAP(AVFrame *, s->frames[VP56_FRAME_CURRENT],

                      s->frames[VP56_FRAME_PREVIOUS]);

    return 0;

}

av_cold int ff_vp56_init_context(AVCodecContext *avctx, VP56Context *s,

                                  int flip, int has_alpha)

{

    int i;

    s->avctx = avctx;

    avctx->pix_fmt = has_alpha ? AV_PIX_FMT_YUVA420P : AV_PIX_FMT_YUV420P;

    if (avctx->skip_alpha) avctx->pix_fmt = AV_PIX_FMT_YUV420P;

    ff_h264chroma_init(&s->h264chroma, 8);

    ff_hpeldsp_init(&s->hdsp, avctx->flags);

    ff_videodsp_init(&s->vdsp, 8);

    ff_vp3dsp_init(&s->vp3dsp);

    for (i = 0; i < 64; i++) {

#define TRANSPOSE(x) (((x) >> 3) | (((x) & 7) << 3))

        s->idct_scantable[i] = TRANSPOSE(ff_zigzag_direct[i]);

#undef TRANSPOSE

    }

    for (i = 0; i < FF_ARRAY_ELEMS(s->frames); i++) {

        s->frames[i] = av_frame_alloc();

        if (!s->frames[i])

            return AVERROR(ENOMEM);

    }

    s->edge_emu_buffer_alloc = NULL;

    s->above_blocks = NULL;

    s->macroblocks = NULL;

    s->quantizer = -1;

    s->deblock_filtering = 1;

    s->golden_frame = 0;

    s->filter = NULL;

    s->has_alpha = has_alpha;

    s->modelp = &s->model;

    if (flip) {

        s->flip = -1;

        s->frbi = 2;

        s->srbi = 0;

    } else {

        s->flip = 1;

        s->frbi = 0;

        s->srbi = 2;

    }

    return 0;

}

av_cold int ff_vp56_free_context(VP56Context *s)

{

    int i;

    av_freep(&s->above_blocks);

    av_freep(&s->macroblocks);

    av_freep(&s->edge_emu_buffer_alloc);

    for (i = 0; i < FF_ARRAY_ELEMS(s->frames); i++)

        av_frame_free(&s->frames[i]);

    return 0;

}